The present invention relates to a support bearing for an elastic connection of vehicle parts, especially for securing a subframe to a vehicle body, in which, even under the influence of relatively high vibrations, the rubber bush in one vehicle part cannot shift in a receiving lug toward the other vehicle part.
Support bearings are shown in United Kingdom Preliminary Publication 2,122,555. In the installed state, the known rubber bush is subjected to shearing stresses. Also, for mounting the bearing in a vehicle part, the rubber bush has to be pressed with a tight fit into a corresponding receiving lug. To this end, the rubber bush is introduced into the receiving lug with its bead-like bush endpiece facing away from the flange of the sheet-metal casing, and the bush endpiece is correspondingly compressed in a radial direction.
When the rubber bush reaches its final installation position, the bead-like bush endpiece comes out of the receiving lug, expands in a radial direction, engages over the edge of the receiving lug and thus forms an axial stop which, together with the flange of the rubber bush bearing on the opposite edge of the receiving lug fixes the rubber bush in its installation position. This axial stop also forms a buffer for a stop plate which is arranged on the clamping screw passing through the bearing core and screwed to the other vehicle part to limit the axial travel of the support bearing in one direction.
In support bearings installed in subframes with their axis in the vertical direction, the rubber bush is exposed to especially high stresses in the axial direction. It is surprising that the flange and bead-like bush endpiece can perfectly well guarantee a reliable axial fixing of the rubber bush under pronounced vertical relative movements between the subframe and vehicle body, whereas the result of axially directed high-frequency vibrations can also be that the rubber bush, although mounted in the receiving lug with a high radial prestress, shifts axially. Thus, the stop formed by the bead-like bush endpiece engaging behind the edge of the receiving lug is thereby overcome, and the bush endpiece is drawn into the receiving lug. Consequently, the buffer provided between the receiving lug and the stop plate arranged on the clamping screw is then absent, and the bearing flexibility in one axial direction is correspondingly reduced. In the event of vertical movements between the vehicle body and subframe, therefore, the stop plate strikes directly against the subframe even after only a relatively small axial travel, thereby considerably restricting driving comfort.
In addition to the support bearing according to G.B. Preliminary Publication 2,122,555, which forms the starting point of the present invention, U.S. Pat. No. 3,479,081 has already made known a support bearing, the rubber bush of which likewise has supporting elements which prevent the possibility that the rubber bush will shift axially in the orifice receiving it. Here, the supporting elements form integral parts of a double-conical sleeve which constitutes the bearing core and the double cone of which is slotted along generatrices. The clamping screw passing through the sleeve is screwed into an internal sleeve thread.
As a result of the tightening of the clamping screw, the sleeve ribs formed by the slots buckle, the sleeve at the same time being shortened axially, and expand the rubber bush radially to such an extent that an axial movement in the orifices receiving it is no longer possible. The screwing of the clamping screw together with the sleeve does not make it possible to fix the bearing core to a vehicle part with a specific pressure force. moreover, in this bearing construction, it is not possible to equip the rubber bush with a sheet metal casing. Finally, this axial flexibility is dependent on the radial bracing of the rubber bush.
An object on which the present invention is based is to improve a support bearing such that, even under the influence of relatively high vibrations, the rubber bush can no longer shift in the receiving lug in the direction of the other vehicle part.
According to the present invention, this object has been achieved by providing the bush endpiece facing away from the flange with supporting elements which, after radial expansion, engage snap-like behind the edge of a receiving lug. At an axial distance from the edge of the receiving lug the supporting elements are adjacent to an abutment provided in the bush endpiece.
The supporting elements provided according to the present invention can be vulcanized onto or into the bush endpiece. They do not hinder the installation of the support bearing in a receiving lug because, when being pushed into the receiving lug, they are shifted appropriately far inward radially as a result of the associated radial deformation of the bush endpiece carrying them. When, after the installation position of the rubber bush is reached, the bush endpiece comes out of the receiving lug and then expands radially correspondingly as a result of its radial prestress previously obtained, the supporting elements are driven in this direction and shifted over the edge of the receiving lug.
There is then no possibility that the bush endpiece will be drawn into the receiving lug or that the rubber bush will shift axially in the lug, especially under the influence of axial vibrations since, under the influence of corresponding shearing forces, the supporting elements are supported on the abutment provided at an axial distance from the edge of the receiving lug, and an effective locking of the rubber bush is thereby maintained.